Balancing ring material consisting of solutions of polystyrene in tetrabromoethane



Patented Oct. 7, 1952 BALANCING RING MATERIAL CONSISTING OF SOLUTIONS OF POLYSTYRENE IN TETRABROMOETHANE Thomas R. Smith, Newton, Iowa, assignor to The Maytag Company, Newton, Iowa, a corporation of Delaware 1 No Drawing.

' 3 Claims. 1

The present invention relates to a new composition of matter, and more particularly to fluid material for use in balancing rings for centrifuging machines.

Among the objects of the present invention is to provide a balancing fluid having a relatively high viscosity for use in balancin rings to compensate for unbalanced loads such, for example, as experienced in automatic washing machines having a tub adapted to be rotated at relatively high speeds for drying clothes and the like.

Another object of the invention is to provide a balancing fluid in which the basic component consists of tetrabromoethane to which is added a polystyrene to produce a fluid particularly adapted for use as a balancing medium for centrifuging machines, such fluid material being characterized by having good aging stability, one which decreases the corrosive effect of tetrabromoethane on steel, and one which can be manufactured at a relatively low cost with a relatively small loss in the specific gravity of the tetrabromoethane.

Other objects, features, capabilities and advantages are comprehended by the invention, as will later appear and as are inherently possessed thereby.

The present invention is directed to the formation of a novel fluid material which is particularly adapted for use as a balancing fluid for centrifuging machines. In the operation of automatic washing machines, for example, where washing and rinsing steps are followed by rapid rotation of the tub to dry the material being washed, the clothes or other material are disposed within the tubein such a manner as to produce an unbalanced condition which causes wobbling or gyratory movement of the tub as the same is brought up to operating speeds for drying the clothes or other material. In order to compensate for these unbalanced loads, it has been found desirable to use a balancing ring of tubular construction mounted adjacent the top and on the outside of the tub and to place within the ring a fluid material having a relatively high specific gravity to compensate for such unbalanced loads and to prevent excessive wobbling or gyratory movement of the tub as the same is brought up to operating speeds for drying the clothes or other material.

Various types of material have been used, but the present invention has for its primary object the idea of providing a fluid material at a relatively low cost, yet one which has the desired viscosity, stability and corrosive resistant prop- Application December '7, 1949, Serial No. 131,687

erties for the use indicated. Such fluid material consists of tetrabromoethane and a polystyrene of relatively high molecular weight. The tetrabromoethane has an average specific gravity of approximately 2.962 at 25 C. and has an aver.- age viscosity of 30 centipoises at the same temperature. Preferably, th polystyrene used has an average molecular weight of 85,000 and is added to the tetrabromoethane by stirring or agitation. Heating the tetrabromoethane to a temperature of between 162 and 180 F. increases the rate at which the polystyrene is dissolved in the tetrabromoethane. While there is some question as to whether the resulting mixture of tetrabromoethane and polystyrene is a true solution, nevertheless, the two components cannot be separated when the same are put through a centrifuge. For the purpose of this application, the fluid material has been referred to and defined as a solution.

The tetrabromoethane and the polystyrene may be mixed in various proportions, it being preferred to use the polystyrene in an amount varying from 5 to 5% per cent by weight of the solution, which results in a solution having a viscosity of from approximately 2,900 to 4,000 centipoises at 25 C., as measured by a Brookfield viscosimeter, and having a minimum specific gravity of 2.70 at the same temperature. It has been found that a solution of these two components having a viscosity of approximately 2,900 centipoiscs with a specific gravity somewhat above 2.70 provides a satisfactory fluid material for use in balancing rings and will compensate for the major portion of unbalanced washing loads of automatic washing machines of the domestic type.

The polystyrene having an average molecular weight as above indicated may be purchased on the open market, one such polystyrene being known by the trade name Styron PS-- which is manufactured and sold by the Dow Chemical Company. This polystyrene, when added to tetrabromoethane, was found to give good aging stability to the tetrabromoethane and decreased the corrosive effect of the tetrabromoethane on steel. It was also found to produce good thickening of the tetrabromoethane with a small loss in specific gravity and can be purchased at relatively low cost per pound.

The principal reason for increasing the viscosity of the tetrabromoethane in the manner indicated is to make the same capable of acting as its own dampening agent so that it does not respond too quickly to the unbalanced condition of The resulting solution of tetrabromomethane.

and the polystyrene indicated is added to the annular balancing ring in any desired amount to prevent excessive wobbling or gyratory movement of the washing tub due to unbalanced load conditions. The size of the balancing ring and the amount used will, of course, depend upon the design of the washing tub, the unbalanced load to:

be compensated, as well as various operating conditions for the particular centrifuging machine; While I have herein described an illustrative example-of the invention, it is to be understood that the invention is not limited thereto but may comprehend other preparations, details, features and method steps without departing fromthe spirit of theinvention.

It'is claimed: 1; Asa new composition of matter, a solution consisting of tetrabromethane and a polystyrene in an amount of approximately 5 to 5% per cent by weight of the solution.

2. As a new composition of matter, a solution consisting of tetrabromethjane' anda polystyrene in an amount of approximately 5' to 5 /4 per cent by weight of the solution and characterized by having a specific gravity of not less than about 2.70 and a viscosity-of not less than about 2,900 centipoises at 25 C.

3. As'a new-composition of matter, a solution consisting of tetrabromoethane and a polystyrene havingan average molecular weight in the neighborhood of 85,000 in an amount of approximately 5 to 5% per cent by weight of the solutionand characterized by having a specific gravityof not less than about 2.70 and a viscosity of not less than about 2,900 centipoises at 25 C.

THOMAS R. SMITH.

REFERENCES CITED The following'references are of record in the" Number Country Date Great Britain July"12,'1943 

1. AS A NEW COMPOSITION OF MATTER, A SOLUTION CONSISTING OF TETRABROMETHANE AND A POLYRENE IN AN AMOUNT OF APPROXIMATELY 5 TO 5 1/4 PER CENT BY WEIGHT OF THE SOLUTION. 